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Abstract: An efficient and practical method for construction of 2-arylbenzo[b]furans from 2-methoxychalcone epoxides has been reported. Catalyzed by 2 mol % of BF3·Et2O, 2-methoxychalcone epoxides went through the Meerwein rearrangement, followed by deformylation in one-pot to successfully afforded 2-methoxydeoxybenzoins. Afterward, 2-arylbenzo[b]furans were obtained in high yields (87%–100%) via intermolecular cyclodehydration of 2-methoxydeoxybenzoins with 48% HBr. By utilization of this approach, the natural product stemofuran A and the key intermediate of eupomatenoid 6 have been synthesized conveniently. [Copyright &y& Elsevier]

Abstract: An interesting rhodium(I)-catalyzed [3+2] intramolecular cycloaddition of alkylidenecyclopropanes 1 containing propargylic esters has been described in this context. A variety of bicyclo[3.3.0]octene derivatives were obtained in moderate to good yields under mild conditions. The alkylidenecyclopropane-enynes 2 could be also converted to the corresponding cycloadducts 3 in good yields. [Copyright &y& Elsevier]

Abstract: Cinchona alkaloid derived catalyst cat. 5 prepared from β-isocupreidine (β-ICD) was found to be a fairly effective organocatalyst for the nucleophilic promoted asymmetric [4+2] cycloaddition reaction of salicyl N-tosylimines and allenic esters to give the corresponding adducts in up to 80% yield, 87% ee. [Copyright &y& Elsevier]

Abstract: Chiral C 2-symmetric diphenylthiophosphoramide ligand L1 prepared from C 2-symmetric (1S,2S)-(−)-1,2-diphenylethylenediamine was found to be a fairly effective chiral ligand for Cu(I)-promoted 1,3-dipolar cycloaddition of imines and pyrrole-2,5-dione derivatives to give the corresponding adducts in moderate enantioselectivities and good yields. [Copyright &y& Elsevier]

An efficient and highly regioselective synthetic method has been developed for the preparation of novel cyclobutene-containing spiro[2.3]hexenes fused with six or seven-membered carbo- or hetero-cycles in good to excellent yields following a thermal induced intramolecular [2+2] cycloaddition of alkynone-vinylidenecyclopropanes or a sequential oxidation/thermal induced intramolecular [2+2] cycloaddition process of propynol-vinylidenecyclopropanes under metal-free conditions. [ABSTRACT FROM AUTHOR]

Abstract: An efficient method for preparation of 3-formyl-2-arylbenzo[b]furan derivatives 4 from 3-chloro-2-(2-methoxyaryl)-1-arylprop-2-en-1-one 2 was developed, and the desired product was obtained in good to excellent yields. By converting 2-(2-methoxyphenyl)-3-oxo-3-phenylpropanal 1 to 2, the regioselectivity problem occurring in the reaction when using 1 as the starting material was successfully avoided. Furthermore, a one-pot procedure for the successive demethylation, cyclization, and hydrolysis was evolved, although the intermediate 3-(dibromomethyl)-2-phenylbenzo[b]furan 3a could be isolated. A plausible mechanism was proposed based on some in situ investigations. [Copyright &y& Elsevier]

Abstract: One-pot thermal-induced [3+2] cycloaddition/silica gel-promoted fragmentation sequence between isatin ketonitrones and electron-deficient alkynes affords spiro[indoline]oxindoles in moderate to excellent yields along with good diastereoselectivities. The detailed mechanism of silica gel-promoted fragmentation has been clarified by experiment and DFT calculations. [Copyright &y& Elsevier]

Abstract: Cyclization reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with ethyl 2,3-butadienoate and allenylsulfone proceeded smoothly in the presence of tertiary phosphine and sodium p-toluenesulfinate (SPTS) to give the corresponding quaternary carbon centered chromans in moderate to good yields under mild conditions, which provides an alternative efficient approach for the synthesis of biologically active chroman products. [Copyright &y& Elsevier]

Abstract: In this paper, we reported that phosphorus-containing Lewis bases catalyzed [4+2] cyclization of N-protected isatin derived electron-deficient alkenes with but-3-yn-2-one could proceed smoothly to give the corresponding dihydropyrano[2,3-b]indoles in good to excellent yields under mild conditions. The substrate scope has been carefully examined and the plausible reaction mechanism has been also proposed. [Copyright &y& Elsevier]

Abstract: The reaction of isoquinoline and allenoate with activated ketone resulted in a novel three component reaction, affording [1,3]oxazino[2,3-a]isoquinoline derivatives in moderate yields along with moderate diastereoselectivities via 1,4-dipolar cycloaddition. It was also found that when isatins were used as substrates, the regioselectivity of cycloadducts was different from those using ethyl trifluoropyruvate as substrate. [Copyright &y& Elsevier]

Abstract: A class of axially chiral NHC–Au(I) complexes has been applied to the asymmetric Friedel–Crafts/cyclization reaction of nitrogen-tethered 1,6-enynes 14 with indole derivatives 15, affording the corresponding Friedel–Crafts and intramolecular cyclization products 16 in good yields and with moderate ee values under mild conditions. [Copyright &y& Elsevier]

The first conjugate addition of α-isocyanoacetates with in situ generated azoalkenes from α-halogeno hydrazones in the presence of Cs 2 CO 3 has been developed. The reaction condition was suitable to various α-aryl substituted isocyanoacetates as well as aryl and alkyl-substituted α-halogeno hydrazones, affording the corresponding products in good to high yields. The adducts can be easily transformed into biologically attractive 1,4-dihydropyrimidine derivatives via an intramolecular cyclization by treating with AgOAc. The one-pot conjugate addition/intramolecular cyclization has also been investigated to furnish the formal [3 + 3] cycloadduct, 1,4-dihydropyrimidine derivatives. [Display omitted] [ABSTRACT FROM AUTHOR]